blob: 5294de1f40c41ba3c2dfcd992c725202967b0dce [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/libfs.c
3 * Library for filesystems writers.
4 */
5
6#include <linux/module.h>
7#include <linux/pagemap.h>
8#include <linux/mount.h>
9#include <linux/vfs.h>
Ingo Molnar7cf34c72006-03-23 03:00:36 -080010#include <linux/mutex.h>
11
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <asm/uaccess.h>
13
14int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
15 struct kstat *stat)
16{
17 struct inode *inode = dentry->d_inode;
18 generic_fillattr(inode, stat);
19 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
20 return 0;
21}
22
David Howells726c3342006-06-23 02:02:58 -070023int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -070024{
David Howells726c3342006-06-23 02:02:58 -070025 buf->f_type = dentry->d_sb->s_magic;
Linus Torvalds1da177e2005-04-16 15:20:36 -070026 buf->f_bsize = PAGE_CACHE_SIZE;
27 buf->f_namelen = NAME_MAX;
28 return 0;
29}
30
31/*
32 * Retaining negative dentries for an in-memory filesystem just wastes
33 * memory and lookup time: arrange for them to be deleted immediately.
34 */
35static int simple_delete_dentry(struct dentry *dentry)
36{
37 return 1;
38}
39
40/*
41 * Lookup the data. This is trivial - if the dentry didn't already
42 * exist, we know it is negative. Set d_op to delete negative dentries.
43 */
44struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
45{
46 static struct dentry_operations simple_dentry_operations = {
47 .d_delete = simple_delete_dentry,
48 };
49
50 if (dentry->d_name.len > NAME_MAX)
51 return ERR_PTR(-ENAMETOOLONG);
52 dentry->d_op = &simple_dentry_operations;
53 d_add(dentry, NULL);
54 return NULL;
55}
56
57int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
58{
59 return 0;
60}
61
62int dcache_dir_open(struct inode *inode, struct file *file)
63{
64 static struct qstr cursor_name = {.len = 1, .name = "."};
65
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080066 file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067
68 return file->private_data ? 0 : -ENOMEM;
69}
70
71int dcache_dir_close(struct inode *inode, struct file *file)
72{
73 dput(file->private_data);
74 return 0;
75}
76
77loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
78{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080079 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 switch (origin) {
81 case 1:
82 offset += file->f_pos;
83 case 0:
84 if (offset >= 0)
85 break;
86 default:
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080087 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 return -EINVAL;
89 }
90 if (offset != file->f_pos) {
91 file->f_pos = offset;
92 if (file->f_pos >= 2) {
93 struct list_head *p;
94 struct dentry *cursor = file->private_data;
95 loff_t n = file->f_pos - 2;
96
97 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -080098 list_del(&cursor->d_u.d_child);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -080099 p = file->f_path.dentry->d_subdirs.next;
100 while (n && p != &file->f_path.dentry->d_subdirs) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800102 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 if (!d_unhashed(next) && next->d_inode)
104 n--;
105 p = p->next;
106 }
Eric Dumazet5160ee62006-01-08 01:03:32 -0800107 list_add_tail(&cursor->d_u.d_child, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 spin_unlock(&dcache_lock);
109 }
110 }
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800111 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 return offset;
113}
114
115/* Relationship between i_mode and the DT_xxx types */
116static inline unsigned char dt_type(struct inode *inode)
117{
118 return (inode->i_mode >> 12) & 15;
119}
120
121/*
122 * Directory is locked and all positive dentries in it are safe, since
123 * for ramfs-type trees they can't go away without unlink() or rmdir(),
124 * both impossible due to the lock on directory.
125 */
126
127int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
128{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800129 struct dentry *dentry = filp->f_path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 struct dentry *cursor = filp->private_data;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800131 struct list_head *p, *q = &cursor->d_u.d_child;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 ino_t ino;
133 int i = filp->f_pos;
134
135 switch (i) {
136 case 0:
137 ino = dentry->d_inode->i_ino;
138 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
139 break;
140 filp->f_pos++;
141 i++;
142 /* fallthrough */
143 case 1:
144 ino = parent_ino(dentry);
145 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
146 break;
147 filp->f_pos++;
148 i++;
149 /* fallthrough */
150 default:
151 spin_lock(&dcache_lock);
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700152 if (filp->f_pos == 2)
153 list_move(q, &dentry->d_subdirs);
154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
156 struct dentry *next;
Eric Dumazet5160ee62006-01-08 01:03:32 -0800157 next = list_entry(p, struct dentry, d_u.d_child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 if (d_unhashed(next) || !next->d_inode)
159 continue;
160
161 spin_unlock(&dcache_lock);
Ronni Nielsen0f8952c22007-05-09 06:44:57 +0200162 if (filldir(dirent, next->d_name.name,
163 next->d_name.len, filp->f_pos,
164 next->d_inode->i_ino,
165 dt_type(next->d_inode)) < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 return 0;
167 spin_lock(&dcache_lock);
168 /* next is still alive */
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700169 list_move(q, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 p = q;
171 filp->f_pos++;
172 }
173 spin_unlock(&dcache_lock);
174 }
175 return 0;
176}
177
178ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
179{
180 return -EISDIR;
181}
182
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800183const struct file_operations simple_dir_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 .open = dcache_dir_open,
185 .release = dcache_dir_close,
186 .llseek = dcache_dir_lseek,
187 .read = generic_read_dir,
188 .readdir = dcache_readdir,
Hugh Dickins8ae0b772005-06-25 14:55:41 -0700189 .fsync = simple_sync_file,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190};
191
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800192const struct inode_operations simple_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 .lookup = simple_lookup,
194};
195
Hugh Dickins759b9772007-03-05 00:30:28 -0800196static const struct super_operations simple_super_operations = {
197 .statfs = simple_statfs,
198};
199
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200/*
201 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
202 * will never be mountable)
203 */
David Howells454e2392006-06-23 02:02:57 -0700204int get_sb_pseudo(struct file_system_type *fs_type, char *name,
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800205 const struct super_operations *ops, unsigned long magic,
David Howells454e2392006-06-23 02:02:57 -0700206 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207{
208 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 struct dentry *dentry;
210 struct inode *root;
211 struct qstr d_name = {.name = name, .len = strlen(name)};
212
213 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700214 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
216 s->s_flags = MS_NOUSER;
217 s->s_maxbytes = ~0ULL;
218 s->s_blocksize = 1024;
219 s->s_blocksize_bits = 10;
220 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800221 s->s_op = ops ? ops : &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 s->s_time_gran = 1;
223 root = new_inode(s);
224 if (!root)
225 goto Enomem;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700226 /*
227 * since this is the first inode, make it number 1. New inodes created
228 * after this must take care not to collide with it (by passing
229 * max_reserved of 1 to iunique).
230 */
231 root->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
233 root->i_uid = root->i_gid = 0;
234 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
235 dentry = d_alloc(NULL, &d_name);
236 if (!dentry) {
237 iput(root);
238 goto Enomem;
239 }
240 dentry->d_sb = s;
241 dentry->d_parent = dentry;
242 d_instantiate(dentry, root);
243 s->s_root = dentry;
244 s->s_flags |= MS_ACTIVE;
David Howells454e2392006-06-23 02:02:57 -0700245 return simple_set_mnt(mnt, s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246
247Enomem:
248 up_write(&s->s_umount);
249 deactivate_super(s);
David Howells454e2392006-06-23 02:02:57 -0700250 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251}
252
253int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
254{
255 struct inode *inode = old_dentry->d_inode;
256
257 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -0700258 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 atomic_inc(&inode->i_count);
260 dget(dentry);
261 d_instantiate(dentry, inode);
262 return 0;
263}
264
265static inline int simple_positive(struct dentry *dentry)
266{
267 return dentry->d_inode && !d_unhashed(dentry);
268}
269
270int simple_empty(struct dentry *dentry)
271{
272 struct dentry *child;
273 int ret = 0;
274
275 spin_lock(&dcache_lock);
Eric Dumazet5160ee62006-01-08 01:03:32 -0800276 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 if (simple_positive(child))
278 goto out;
279 ret = 1;
280out:
281 spin_unlock(&dcache_lock);
282 return ret;
283}
284
285int simple_unlink(struct inode *dir, struct dentry *dentry)
286{
287 struct inode *inode = dentry->d_inode;
288
289 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700290 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 dput(dentry);
292 return 0;
293}
294
295int simple_rmdir(struct inode *dir, struct dentry *dentry)
296{
297 if (!simple_empty(dentry))
298 return -ENOTEMPTY;
299
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700300 drop_nlink(dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 simple_unlink(dir, dentry);
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700302 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 return 0;
304}
305
306int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
307 struct inode *new_dir, struct dentry *new_dentry)
308{
309 struct inode *inode = old_dentry->d_inode;
310 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
311
312 if (!simple_empty(new_dentry))
313 return -ENOTEMPTY;
314
315 if (new_dentry->d_inode) {
316 simple_unlink(new_dir, new_dentry);
317 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700318 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700320 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -0700321 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 }
323
324 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
325 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
326
327 return 0;
328}
329
330int simple_readpage(struct file *file, struct page *page)
331{
Pekka J Enbergc0d92cb2006-09-29 01:59:09 -0700332 clear_highpage(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 flush_dcache_page(page);
334 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 unlock_page(page);
336 return 0;
337}
338
339int simple_prepare_write(struct file *file, struct page *page,
340 unsigned from, unsigned to)
341{
342 if (!PageUptodate(page)) {
343 if (to - from != PAGE_CACHE_SIZE) {
344 void *kaddr = kmap_atomic(page, KM_USER0);
345 memset(kaddr, 0, from);
346 memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
347 flush_dcache_page(page);
348 kunmap_atomic(kaddr, KM_USER0);
349 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 }
351 return 0;
352}
353
354int simple_commit_write(struct file *file, struct page *page,
Nick Piggin955eff52007-02-20 13:58:08 -0800355 unsigned from, unsigned to)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356{
357 struct inode *inode = page->mapping->host;
358 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
359
Nick Piggin955eff52007-02-20 13:58:08 -0800360 if (!PageUptodate(page))
361 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 /*
363 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800364 * cannot change under us because we hold the i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 */
366 if (pos > inode->i_size)
367 i_size_write(inode, pos);
368 set_page_dirty(page);
369 return 0;
370}
371
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700372/*
373 * the inodes created here are not hashed. If you use iunique to generate
374 * unique inode values later for this filesystem, then you must take care
375 * to pass it an appropriate max_reserved value to avoid collisions.
376 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
378{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 struct inode *inode;
380 struct dentry *root;
381 struct dentry *dentry;
382 int i;
383
384 s->s_blocksize = PAGE_CACHE_SIZE;
385 s->s_blocksize_bits = PAGE_CACHE_SHIFT;
386 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800387 s->s_op = &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 s->s_time_gran = 1;
389
390 inode = new_inode(s);
391 if (!inode)
392 return -ENOMEM;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700393 /*
394 * because the root inode is 1, the files array must not contain an
395 * entry at index 1
396 */
397 inode->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 inode->i_mode = S_IFDIR | 0755;
399 inode->i_uid = inode->i_gid = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 inode->i_blocks = 0;
401 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
402 inode->i_op = &simple_dir_inode_operations;
403 inode->i_fop = &simple_dir_operations;
Vincent Hanquez7656f322006-02-03 03:04:48 -0800404 inode->i_nlink = 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 root = d_alloc_root(inode);
406 if (!root) {
407 iput(inode);
408 return -ENOMEM;
409 }
410 for (i = 0; !files->name || files->name[0]; i++, files++) {
411 if (!files->name)
412 continue;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700413
414 /* warn if it tries to conflict with the root inode */
415 if (unlikely(i == 1))
416 printk(KERN_WARNING "%s: %s passed in a files array"
417 "with an index of 1!\n", __func__,
418 s->s_type->name);
419
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 dentry = d_alloc_name(root, files->name);
421 if (!dentry)
422 goto out;
423 inode = new_inode(s);
424 if (!inode)
425 goto out;
426 inode->i_mode = S_IFREG | files->mode;
427 inode->i_uid = inode->i_gid = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 inode->i_blocks = 0;
429 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
430 inode->i_fop = files->ops;
431 inode->i_ino = i;
432 d_add(dentry, inode);
433 }
434 s->s_root = root;
435 return 0;
436out:
437 d_genocide(root);
438 dput(root);
439 return -ENOMEM;
440}
441
442static DEFINE_SPINLOCK(pin_fs_lock);
443
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400444int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445{
446 struct vfsmount *mnt = NULL;
447 spin_lock(&pin_fs_lock);
448 if (unlikely(!*mount)) {
449 spin_unlock(&pin_fs_lock);
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400450 mnt = vfs_kern_mount(type, 0, type->name, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 if (IS_ERR(mnt))
452 return PTR_ERR(mnt);
453 spin_lock(&pin_fs_lock);
454 if (!*mount)
455 *mount = mnt;
456 }
457 mntget(*mount);
458 ++*count;
459 spin_unlock(&pin_fs_lock);
460 mntput(mnt);
461 return 0;
462}
463
464void simple_release_fs(struct vfsmount **mount, int *count)
465{
466 struct vfsmount *mnt;
467 spin_lock(&pin_fs_lock);
468 mnt = *mount;
469 if (!--*count)
470 *mount = NULL;
471 spin_unlock(&pin_fs_lock);
472 mntput(mnt);
473}
474
475ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
476 const void *from, size_t available)
477{
478 loff_t pos = *ppos;
479 if (pos < 0)
480 return -EINVAL;
481 if (pos >= available)
482 return 0;
483 if (count > available - pos)
484 count = available - pos;
485 if (copy_to_user(to, from + pos, count))
486 return -EFAULT;
487 *ppos = pos + count;
488 return count;
489}
490
491/*
492 * Transaction based IO.
493 * The file expects a single write which triggers the transaction, and then
494 * possibly a read which collects the result - which is stored in a
495 * file-local buffer.
496 */
497char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
498{
499 struct simple_transaction_argresp *ar;
500 static DEFINE_SPINLOCK(simple_transaction_lock);
501
502 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
503 return ERR_PTR(-EFBIG);
504
505 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
506 if (!ar)
507 return ERR_PTR(-ENOMEM);
508
509 spin_lock(&simple_transaction_lock);
510
511 /* only one write allowed per open */
512 if (file->private_data) {
513 spin_unlock(&simple_transaction_lock);
514 free_page((unsigned long)ar);
515 return ERR_PTR(-EBUSY);
516 }
517
518 file->private_data = ar;
519
520 spin_unlock(&simple_transaction_lock);
521
522 if (copy_from_user(ar->data, buf, size))
523 return ERR_PTR(-EFAULT);
524
525 return ar->data;
526}
527
528ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
529{
530 struct simple_transaction_argresp *ar = file->private_data;
531
532 if (!ar)
533 return 0;
534 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
535}
536
537int simple_transaction_release(struct inode *inode, struct file *file)
538{
539 free_page((unsigned long)file->private_data);
540 return 0;
541}
542
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200543/* Simple attribute files */
544
545struct simple_attr {
546 u64 (*get)(void *);
547 void (*set)(void *, u64);
548 char get_buf[24]; /* enough to store a u64 and "\n\0" */
549 char set_buf[24];
550 void *data;
551 const char *fmt; /* format for read operation */
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800552 struct mutex mutex; /* protects access to these buffers */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200553};
554
555/* simple_attr_open is called by an actual attribute open file operation
556 * to set the attribute specific access operations. */
557int simple_attr_open(struct inode *inode, struct file *file,
558 u64 (*get)(void *), void (*set)(void *, u64),
559 const char *fmt)
560{
561 struct simple_attr *attr;
562
563 attr = kmalloc(sizeof(*attr), GFP_KERNEL);
564 if (!attr)
565 return -ENOMEM;
566
567 attr->get = get;
568 attr->set = set;
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700569 attr->data = inode->i_private;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200570 attr->fmt = fmt;
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800571 mutex_init(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200572
573 file->private_data = attr;
574
575 return nonseekable_open(inode, file);
576}
577
578int simple_attr_close(struct inode *inode, struct file *file)
579{
580 kfree(file->private_data);
581 return 0;
582}
583
584/* read from the buffer that is filled with the get function */
585ssize_t simple_attr_read(struct file *file, char __user *buf,
586 size_t len, loff_t *ppos)
587{
588 struct simple_attr *attr;
589 size_t size;
590 ssize_t ret;
591
592 attr = file->private_data;
593
594 if (!attr->get)
595 return -EACCES;
596
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800597 mutex_lock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200598 if (*ppos) /* continued read */
599 size = strlen(attr->get_buf);
600 else /* first read */
601 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
602 attr->fmt,
603 (unsigned long long)attr->get(attr->data));
604
605 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800606 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200607 return ret;
608}
609
610/* interpret the buffer as a number to call the set function with */
611ssize_t simple_attr_write(struct file *file, const char __user *buf,
612 size_t len, loff_t *ppos)
613{
614 struct simple_attr *attr;
615 u64 val;
616 size_t size;
617 ssize_t ret;
618
619 attr = file->private_data;
620
621 if (!attr->set)
622 return -EACCES;
623
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800624 mutex_lock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200625 ret = -EFAULT;
626 size = min(sizeof(attr->set_buf) - 1, len);
627 if (copy_from_user(attr->set_buf, buf, size))
628 goto out;
629
630 ret = len; /* claim we got the whole input */
631 attr->set_buf[size] = '\0';
632 val = simple_strtol(attr->set_buf, NULL, 0);
633 attr->set(attr->data, val);
634out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800635 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200636 return ret;
637}
638
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639EXPORT_SYMBOL(dcache_dir_close);
640EXPORT_SYMBOL(dcache_dir_lseek);
641EXPORT_SYMBOL(dcache_dir_open);
642EXPORT_SYMBOL(dcache_readdir);
643EXPORT_SYMBOL(generic_read_dir);
644EXPORT_SYMBOL(get_sb_pseudo);
645EXPORT_SYMBOL(simple_commit_write);
646EXPORT_SYMBOL(simple_dir_inode_operations);
647EXPORT_SYMBOL(simple_dir_operations);
648EXPORT_SYMBOL(simple_empty);
649EXPORT_SYMBOL(d_alloc_name);
650EXPORT_SYMBOL(simple_fill_super);
651EXPORT_SYMBOL(simple_getattr);
652EXPORT_SYMBOL(simple_link);
653EXPORT_SYMBOL(simple_lookup);
654EXPORT_SYMBOL(simple_pin_fs);
655EXPORT_SYMBOL(simple_prepare_write);
656EXPORT_SYMBOL(simple_readpage);
657EXPORT_SYMBOL(simple_release_fs);
658EXPORT_SYMBOL(simple_rename);
659EXPORT_SYMBOL(simple_rmdir);
660EXPORT_SYMBOL(simple_statfs);
661EXPORT_SYMBOL(simple_sync_file);
662EXPORT_SYMBOL(simple_unlink);
663EXPORT_SYMBOL(simple_read_from_buffer);
664EXPORT_SYMBOL(simple_transaction_get);
665EXPORT_SYMBOL(simple_transaction_read);
666EXPORT_SYMBOL(simple_transaction_release);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200667EXPORT_SYMBOL_GPL(simple_attr_open);
668EXPORT_SYMBOL_GPL(simple_attr_close);
669EXPORT_SYMBOL_GPL(simple_attr_read);
670EXPORT_SYMBOL_GPL(simple_attr_write);